Create new ACL (Access Control List)
------------------------------------
BEGIN
  DBMS_NETWORK_ACL_ADMIN.create_acl (
    acl          => 'acl_for_mymail.xml', 
    description  => 'Create ACL for MyMail Server',
    principal    => 'HR',
    is_grant     => TRUE, 
    privilege    => 'connect',
    start_date   => SYSTIMESTAMP,
    end_date     => NULL);

  COMMIT;
END;
/

Add access point to new ACL
---------------------------
BEGIN
  DBMS_NETWORK_ACL_ADMIN.assign_acl (
    acl => 'acl_for_mymail.xml',
    host => 'smtp.mymail.com', 
    lower_port => 26,
    upper_port => NULL); 
commit;
END;
/

Add privilege
-------------
begin
  dbms_network_acl_admin.add_privilege (
  acl       => 'acl_for_mymail.xml',
  principal => 'HR',
  is_grant  => TRUE,
  privilege => 'connect'
  );
  commit;
end;
/

ALTER SYSTEM SET smtp_out_server = 'smtp.mymail.com';

CREATE OR REPLACE FUNCTION HR.send_email(P_USERID IN VARCHAR2,
                                           P_FROM IN VARCHAR2,
                                             P_TO IN VARCHAR2, 
                                        P_SUBJECT IN VARCHAR2, 
                                            P_MSG IN VARCHAR2,
                                       P_FILENAME IN VARCHAR2)
RETURN VARCHAR2
AS
  V_MAIL_HOST VARCHAR2 (64); 
  V_PORT PLS_INTEGER;
  V_ACCOUNT VARCHAR2(500);
  V_PWD VARCHAR2(500);
  V_MAIL_CONN UTL_SMTP.CONNECTION;
  V_USER VARCHAR2(200);
  V_PASS VARCHAR2(200);
  TYPE T IS TABLE OF VARCHAR2(50);
  T_TO T := T();
  V_COUNT PLS_INTEGER :=1;
  P_MAIL_TO VARCHAR2(2000) := P_TO;
  V_TEST VARCHAR2(60);
  -- mime blocks (the sections of the email body that can become attachments)
  -- must be delimited by a string, this particular string is just an example
  c_mime_boundary CONSTANT VARCHAR2(256) := '-----AABCDEFBBCCC0123456789DE';
  v_clob                   CLOB := EMPTY_CLOB();
  v_len                    INTEGER;
  v_index                  INTEGER;
  p_ret                    VARCHAR2(400);
BEGIN
   ------ X_SERVER, X_PORT, X_ACCOUNT, CRYPTIT.DECRYPT(X_PWD)
   SELECT 'smtp.mymail.com', '26', 'oralover@mymail.com', 'pwd123' 
     INTO V_MAIL_HOST, V_PORT, V_ACCOUNT, V_PWD
     FROM DUAL;
     --FROM hr.GET_SMTP_ACCOUNT
    --WHERE X_USERID = P_USERID;
   --
   -- Build the contents before connecting to the mail server
   -- that way you can begin pumping the data immediately
   -- and not risk an SMTP timeout
   FOR x IN (SELECT *
               FROM all_objects
              WHERE ROWNUM < 20)
   LOOP
       v_clob :=
              v_clob
           || x.owner
           || ','
           || x.object_name
           || ','
           || x.object_type
           || ','
           || TO_CHAR(x.created, 'yyyy-mm-dd hh24:mi:ss')
           || UTL_TCP.crlf;
   END LOOP;
   --
   --
   LOOP
     IF (INSTR(P_MAIL_TO,',') !=0) THEN
        T_TO.EXTEND(1);
        T_TO(V_COUNT) := TRIM(SUBSTR(P_MAIL_TO,1,INSTR(P_MAIL_TO,',') -1));
        P_MAIL_TO := SUBSTR(P_MAIL_TO, INSTR(P_MAIL_TO,',') + 1, LENGTH(P_MAIL_TO) - INSTR(P_MAIL_TO,',') + 1);
        V_COUNT := V_COUNT + 1;
     ELSE
        T_TO.EXTEND(1);
        T_TO(V_COUNT) := TRIM(P_MAIL_TO);
        EXIT;
     END IF;
   END LOOP;
   --
   V_MAIL_CONN := UTL_SMTP.OPEN_CONNECTION(V_MAIL_HOST, V_PORT);
   UTL_SMTP.EHLO(V_MAIL_CONN, V_MAIL_HOST);
   -- 
   UTL_SMTP.COMMAND(V_MAIL_CONN, 'AUTH LOGIN');
   UTL_SMTP.COMMAND(V_MAIL_CONN, UTL_RAW.CAST_TO_VARCHAR2(UTL_ENCODE.BASE64_ENCODE(UTL_RAW.CAST_TO_RAW(V_ACCOUNT))));
   UTL_SMTP.COMMAND(V_MAIL_CONN, utl_raw.cast_to_varchar2(utl_encode.base64_encode( utl_raw.cast_to_raw(v_pwd))));
   V_MAIL_CONN := UTL_SMTP.OPEN_CONNECTION (V_MAIL_HOST, V_PORT);
   UTL_SMTP.HELO (V_MAIL_CONN, V_MAIL_HOST);
   UTL_SMTP.MAIL (V_MAIL_CONN, P_FROM);
   -- send list of repeients ( one or more, comma seperated )
   FOR I IN 1..T_TO.LAST LOOP
       V_TEST := T_TO(I);
       UTL_SMTP.RCPT (V_MAIL_CONN, T_TO(I));
   END LOOP;
   -- 
   UTL_SMTP.OPEN_DATA (V_MAIL_CONN);
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN,
   'Date: '
   || TO_CHAR (SYSDATE, 'DD-MON-YYYY HH24:MI:SS')
   || UTL_TCP.CRLF
   );
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN, 'FROM: ' || P_FROM || UTL_TCP.CRLF);
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN, 'SUBJECT: ' || P_SUBJECT || UTL_TCP.CRLF);
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN, 'TO: ' || P_TO || UTL_TCP.CRLF);
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN, UTL_TCP.CRLF);
   UTL_SMTP.WRITE_DATA (V_MAIL_CONN, P_MSG);
   UTL_SMTP.write_data(
       V_MAIL_CONN,
       'Content-Type: multipart/mixed; boundary="' || c_mime_boundary || '"' || UTL_TCP.crlf
   );
   UTL_SMTP.write_data(V_MAIL_CONN, UTL_TCP.crlf);
   UTL_SMTP.write_data(
       V_MAIL_CONN,
       'This is a multi-part message in MIME format.' || UTL_TCP.crlf
   );
   UTL_SMTP.write_data(V_MAIL_CONN, '--' || c_mime_boundary || UTL_TCP.crlf);
   UTL_SMTP.write_data(V_MAIL_CONN, 'Content-Type: text/plain' || UTL_TCP.crlf);\
   IF P_FILENAME IS NOT NULL THEN
     -- Set up attachment header
     UTL_SMTP.write_data(
         V_MAIL_CONN,
            'Content-Disposition: attachment; filename="'
         || P_FILENAME
         || '"'
         || UTL_TCP.crlf
     );
     UTL_SMTP.write_data(V_MAIL_CONN, UTL_TCP.crlf);
     -- Write attachment contents
     v_len := DBMS_LOB.getlength(v_clob);
     v_index := 1;
     WHILE v_index <= v_len
     LOOP
         UTL_SMTP.write_data(V_MAIL_CONN, DBMS_LOB.SUBSTR(v_clob, 32000, v_index));
         v_index := v_index + 32000;
     END LOOP;
     --
     -- End attachment
   END IF;
   UTL_SMTP.CLOSE_DATA (V_MAIL_CONN);
   UTL_SMTP.QUIT (V_MAIL_CONN);
   p_ret := 'Successfull sent email...';
   return p_ret;
EXCEPTION
    WHEN OTHERS
    THEN
        p_ret := DBMS_UTILITY.format_error_stack;
        return p_ret;
END send_email;
/

Function created.

SQL> ed
Wrote file afiedt.buf

  1  DECLARE
  2      v_mailsever_host VARCHAR2(30) := 'smtp.mymail.com';
  3      v_mailsever_port PLS_INTEGER  := 26;
  4      l_mail_conn  UTL_SMTP.CONNECTION;
  5      v_msg varchar2(200);
  6  BEGIN
  7      l_mail_conn := UTL_SMTP.OPEN_CONNECTION( v_mailsever_host, v_mailsever_port);
  8  EXCEPTION
  9      WHEN OTHERS THEN -- just to check - (do not want to use WHEN OTHERS)
 10      v_msg := DBMS_UTILITY.format_error_stack;
 11      DBMS_OUTPUT.PUT_LINE (v_msg);
 12* END;
SQL>
SQL> /

PL/SQL procedure successfully completed.

SQL> declare
  2    from_user varchar2(50):='MyName';
  3    from_sndr varchar2(50):='oralover@mymail.com';
  4    rcpt_to varchar2(2000):='oralover@mymail.com';
  5    msubj varchar2(80):='This is Subject';
  6    mmsg varchar2(400):= 'I am testing to send email through Oracle SQL...';
  7    ret_msg varchar2(400);
  8    begin
  9      ret_msg := HR.send_email(from_user, from_sndr, rcpt_to, msubj, mmsg, 'abcd.pdf');
 10      dbms_output.put_line(ret_msg);
 11  end;
 12  /
ORA-29279: SMTP permanent error: 550 domain.

PL/SQL procedure successfully completed.

SQL>